The homalonotid trilobite Burmeisteria Salter, 1865 in the Lower Devonian of Argentina: new data in the context of southwestern Gondwana

RUSTÁN, JUAN JOSÉ; WAISFELD, BEATRIZ G.; VACCARI, N. EMILIO

JOURNAL OF PALEONTOLOGY

PALEONTOLOGICAL SOC INC

Año: 2020 vol. 94 p. 498 - 512

0022-3360

The homalonotid trilobite Burmeisteria Salter, 1865 is revised from material from the Lower Devonianof central western Argentina (the Talacasto Formation in the Precordillera Basin). In contrast to other closelyrelated Devonian marine basins from South America (mainly Bolivia, Brazil and Uruguay), the only speciesrecognized in Argentina include Burmeisteria herschelii (Murchison, 1839) and B. notica (Clarke, 1913). New observations on the structure of the carapace indicate that structures sometimes interpreted as granules withtaxonomic meaning are, in fact, taphonomic characters that represent the fillings of pore canals exposed by decortication. The antero-ventral process of the rostral plate may be a locking device during enrollment, which allowedlong-term defensive behavior with a minimum of muscular energy. Burmeisteria is an upper Silurian to MiddleDevonian endemic representative of southwestern Gondwanan (Malvinokaffric) basins. In the Argentine Precordillera Basin, this genus is virtually restricted to a sandy, Pragian, stratigraphic interval capped by a marker bed firstreported by Keidel in 1921.